bsls_timeutil: Add clock_t static_cast.
bsls_timeutil: Add clock_t static_cast.

Add static_cast<clock_t> to ::times return value to silence compiler warning
on OS_DARWIN due to clock_t being unsigned.

minhlongdo/bde,apaprocki/bde,abeels/bde,bloomberg/bde-allocator-benchmarks,RMGiroux/bde-allocator-benchmarks,RMGiroux/bde-allocator-benchmarks,apaprocki/bde,frutiger/bde,abeels/bde,bowlofstew/bde,idispatch/bde,frutiger/bde,dbremner/bde,idispatch/bde,che2/bde,bowlofstew/bde,abeels/bde,saxena84/bde,apaprocki/bde,bloomberg/bde,osubboo/bde,jmptrader/bde,bloomberg/bde,dharesign/bde,minhlongdo/bde,dharesign/bde,saxena84/bde,bloomberg/bde,frutiger/bde,osubboo/bde,dharesign/bde,apaprocki/bde,RMGiroux/bde-allocator-benchmarks,mversche/bde,bloomberg/bde,osubboo/bde,jmptrader/bde,osubboo/bde,apaprocki/bde,gbleaney/Allocator-Benchmarks,gbleaney/Allocator-Benchmarks,gbleaney/Allocator-Benchmarks,minhlongdo/bde,dbremner/bde,abeels/bde,mversche/bde,bloomberg/bde-allocator-benchmarks,idispatch/bde,che2/bde,RMGiroux/bde-allocator-benchmarks,jmptrader/bde,saxena84/bde,bloomberg/bde,abeels/bde,bloomberg/bde-allocator-benchmarks,bloomberg/bde-allocator-benchmarks,che2/bde,mversche/bde,abeels/bde,saxena84/bde,bowlofstew/bde,mversche/bde,dharesign/bde,jmptrader/bde,bowlofstew/bde,che2/bde,bloomberg/bde-allocator-benchmarks,minhlongdo/bde,idispatch/bde,dbremner/bde,gbleaney/Allocator-Benchmarks,dbremner/bde,frutiger/bde,RMGiroux/bde-allocator-benchmarks